Typically, while transferring a document, an image reading apparatus such as a scanner captures an image of the document, using an image capturing device such as a line sensor with imaging elements arranged one-dimensionally. For this reason, a foreign object such as paper powder, dust and paste, etc., attached to a glass surface of the image capturing device may cause vertical stripe noise to appear on a document image obtained by capturing the document.
An image reading apparatus which compares reading data acquired by two CISs arranged to face each other via a transfer path, determines a position where dust attaches, and notifies a user of the determined result is disclosed (refer to Japanese Laid-open Patent Publication No. 2012-204972).